The present invention relates to a connector of an electronic circuit board incorporated in an electronic apparatus such as a computer, and more particularly to a hot pluggable connector which is a connector having terminals to be connected or disconnected sequentially designed for hot-line connection/disconnection.
Some examples of the hot-line connectors are disclosed in Japanese utility model applications laid open as Provisional Publications Nos. 133082/'88, 104478/'82, and 161979/'86.
For the hot-line connection/disconnection (hereafter called the hot plugging), it is required to prevent a power supply voltage variation or a signal disturbance on bus lines because of the hot plugging. For this purpose, in many conventional hot pluggable connectors, terminals provided on an electronic circuit package are designed to be connected sequentially with time differences, so that signal lines, a power supply line, a ground line and so on are connected or disconnected in a predetermined order. For such sequential connection/disconnection of the terminals, however, the electronic circuit package has to be inserted or pulled out within a time limit prescribed for the electronic apparatus in which the electronic circuit package is to be used, which means that the insertion or the pullout must be done very rapidly.
FIG. 8 is a sectional view illustrating an example of a conventional two-piece type hot pluggable connector, wherein a long terminal 11 having a longer contact piece and a short terminal 12 having a shorter contact piece are provided in a board-side connector 3 mounted on a circuit board 7. When a package-side connector 5 mounted on an circuit package 9 is to be engaged with the board-side connector 3, a package-side terminal 13 of the package-side connector 5 is first connected to the long terminal 11 of the board-side connector 3, and then another package-side terminal 14 of the package-side connector 5 is connected to the short terminal 12 of the board-side connector 3. Thus, the short terminal 12 is connected to the package-side terminal 14 after the long terminal 11 is connected to the package-side terminal 13 with a time difference according to a length difference between the long and short terminals 11 and 12.
FIG. 9 is a sectional view illustrating an example of a conventional one-piece type hot pluggable connector, wherein pads on a card-edge of an electronic circuit package 9 are connected to a card-edge connector, that is, a board-side connector 3 having board-side terminals 15 and 16. On the card-edge of the electronic circuit package 9, a long pad 95 and a short pat 96 are arranged at positions which are shifted with each other in the engaging direction, so that the short pad 96 is connected to the board-side terminal 16 sequentially after the long pad 95 is connected to the board-side terminal 15 when the card-edge is engaged with the card-edge connector 3, with a time difference proportional to the positional difference between the long and the short pad 95 and 96.
In the above mentioned Japanese utility model application of the Provisional Publication No. 161979/'86, connector terminals are formed in different shapes for realizing the sequential connection/disconnection. More particularly, a contact point is configured for each of the connector terminals by bending a part thereof, and the positions of the bending parts are so arranged to realize a desired order of the sequential connection/disconnection.
However, the conventional hot pluggable connectors such as above described have various disadvantages as will be described below.
First of all, a considerably large shock may be caused when the conventional hot pluggable connector is plugged or unplugged. This is because the time difference necessary for the sequential connection/disconnection of terminals is defined by length difference among the terminals in a direction parallel to the plug-in direction of the circuit package whereto the hot pluggable connector is provided. Therefore, the circuit package should be plugged or unplugged rapidly within a time limit according to performance and configuration of the electronic apparatus whereto the circuit package is applied, so as to prevent the supply voltage variation, the bus line signal disturbance or the element breakdown of the circuit package.
Secondly, it is required, because of the same reason, to reinforce anti-shock performance of the circuit board having the conventional hot pluggable connector whereto the circuit package is plugged in, or to provide an effective mechanism for preventing the neighboring packages loosing off from the electronic apparatus. Furthermore, when the plugging/unplugging time limit is more strict, a special tool may be needed for plugging or unplugging the circuit package, resulting in a high cost.
Thirdly, such quick plugging or unplugging of a circuit package may possibly cause damages in the wiring pattern of the circuit package and degrade the reliability of packaged elements. This disadvantage also comes from the above-mentioned reason that the time difference for the sequential connection/disconnection is defined by length difference of the terminals in the direction parallel to the plug-in direction.
Fourthly, the conventional hot pluggable connectors are more expensive compared to the ordinary connectors. This is because they use more parts than the ordinary connectors, including a plurality of terminals different in length or bent position with each other, prepared for the sequential connection/disconnection thereof.
Fifthly, when the terminal length once set for a sequential connection/disconnection has to be changed later, a new set of terminals having new terminal length must be prepared again for the new sequence. This is because the sequential connection/disconnection is defined by length difference of the terminals in the conventional hot pluggable connector.